Ceramic multichip module MCM

Figure 5.6 Example of a ceramic multichip module (MCM-C) and a hybrid microcircuit. Top MCM-C fabricated from high-temperature cofired ceramic. Source Honeywell Sohd State Electronics Center. Bottom Multilayer thick-film hybrid microcircuit.

Pricing as well as reliability considerations have led to an almost exclusive use of Si-based (i.e. Si and SOI) micro machined devices. Packaging and assembly has focused on ceramics (A1203, AIN, Low Temperature Co-fired Ceramics LTCC), Printed Circuit Board (PCB-) and Surface Mount Device (SMD-) technology and multichip modules (MCM s). 

Substrates made by the multilayer process from tape cast alumina have received considerable attention in recent years for multichip module (MCM) applications. An MCM consists of an array of closely packed chips on an interconnect board several inches on a side. Cofired ceramic is attractive relative to organic laminates because its thermal conductivity is almost 2 orders of magnitude higher, an important consideration in high-density circuitry. In addition both alumina and aluminum nitride ceramics are more closely matched to silicon in CTE than are organic boards. For similar reasons, alumina and AIN are attractive for ball grid array (EGA) mounting of chips. ... 

MCM-D/C, Multichip Module Deposited and Cofired. This version of an MCM is a combination of a cofired, mnltilayer ceramic snbstrate containing the common wiring for a family of modules and deposited conductor and insnlation layers containing the personality wiring. It has all of the problems of each technology it nses pins problems related to mismatches in temperature coefficient of the two materials systems. 

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